Modular staircase system

ABSTRACT

A modular staircase system configured to form a curved staircase, support extremely heavy finishing materials, having higher design tolerances, and can be achieved at a relatively moderate cost. A plurality of stair modules are configured to secure to one another to form a complete staircase system, each which has an elaborate stringer of significant strength and moderate weight configurable to create floating staircases at an affordable cost.

FIELD OF THE INVENTION

The present invention generally relates to staircase systems utilized inthe building industry.

BACKGROUND OF THE INVENTION

A conventional staircase system includes a plurality ofascending/descending steps laterally extending between a pair ofstringers, each of the steps include a tread portion and a riserportion. Stairs are expensive due to the high cost of the materials, aswell as the skilled labor required to make and construct such systems.The labor can easily exceed the cost of the materials in even the mostbasic staircase systems. As the complexity of the staircase increases,including designing curves, landings, and floating stair systems, theprice exponentially escalates due to the cost of the materials, thewasted materials, and the additional labor.

Staircase systems area complex works of art. Stair owners have unlimitedchoices of material to cover their stair with. It could be as simple asoak treads, oak riser, oak skirt boards, oak balusters, and oakhandrails, to as complex as Italian Marble treads, Italian marblerisers, Italian marble skirt board, Italian marble balustrade andItalian marble handrails. When considering the different types ofmaterials, the load factor for the two stairs described above are at twoends of the scale. Stair builders utilize wood stringers and risers orsteel stringers and risers to carry the loads associated with the chosenmaterials. With the complexity of building and designing stair systems,many of the stairs are fabricated off site and then transported to thejob site and then installed.

In high-end staircase systems, curved stringers are often made fromlarge expensive cold rolled steel. Steel stringers which may extend inthe vertical direction in excess of 12 feet lineally extend 20 feet ormore. These metal stringers are extremely difficult to tool given boththe tooling tolerances, as well as the variations of the material overtemperature. The longer the stringer, the more likely that tolerancescan lead to a staircase that fails to meet the design requirements inits intended location. Given the extreme pricing of the tooling and thesteel stock, it is an expensive task to simply scrap the stringer. Moreelaborate designs include multiple landings, which increase the staircomplexity and loading requirements.

SUMMARY OF INVENTION

The present invention achieves technical advantages as a modularstaircase system which may be configured to form a curved staircase,support extremely heavy finishing materials, having high designtolerances, and which can be constructed at a relatively moderate cost.A plurality of stair modules are configured to secure to one another toform a complete staircase system, each module having an elaborate framedstringer of significant strength and moderate weight, configurable tocreate eloquent floating staircases at an affordable cost. The stringersmay be formed of steel tread flanges and riser flanges to form a steelframed stringer. The tread flanges and riser flanges may form arectangular frame defining an opening, adapted to receive an outerfascia member, and support a riser and tread extending therebetween.This metal framed stringer can be designed to be curved to extremelytight tolerances and support extremely heavy loads, and easily assembledas a complex staircase at the fabricator, disassembled for convenienttransport, and reassembled at its intended location with moderateeffort. Because the steel stringers are framed, the cost of materials isreduced without sacrificing strength, and the curve can be designed to atight tolerance using computer aided tooling equipment. Staircasesdesigned according to the present invention can realize up to an 40%savings in materials and 50% savings in labor compared to conventionalstaircase systems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a planar view of a modular curved staircase system accordingto one preferred embodiment of the present invention;

FIG. 2 is a top view of the staircase system of FIG. 1 with the risersand treads removed to expose the framed stringers in modularconstruction;

FIG. 3 is a view of the underside of the staircase system shown in FIG.2 detailing the laterally extending t-astragals extending between thestringers, as well as the hardware for securing one modular stairsection to the next;

FIG. 4 is an enlarged view of one modular stair section of the staircaseshown in FIG. 1 with the treads and risers removed;

FIG. 5 is a perspective view of a single stair module with the riser andtread portions removed;

FIG. 6 is a perspective view of a single stair module with a unitaryriser and tread portion adapted to and supported by the framedstringers;

FIG. 7 is a perspective view of a single stair section with a unitaryriser/tread adapted over each step and supported by the framedstringers;

FIG. 8 is a perspective view of a staircase system according to a secondpreferred embodiment including modular stair sections and a plurality ofmodular landing sections; and

FIG. 9 is an enlarged view of a landing section extending between twomodular stair sections shown in FIG. 8.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Referring now to FIG. 1, there is generally shown at 10 a modularstaircase system according to one preferred embodiment of the presentinvention. System 10 is seen to be comprised of a plurality of stairsections generally shown at 12 assembled and secured to one another tocreate a floating staircase with continuous ascending steps generallyshown at 14. Each step 14 has a riser portion 16 and a tread portion 18,as shown. In this preferred embodiment, each stair section 12 has threesteps 14, although more or less steps could be included in the stairsection 12 as desired and as a function of the overall staircase design.Staircase system 10 derives technical advantages in that a complexstaircase system can be achieved utilizing modular stair sections, eachsection being tooled to very tight tolerances, configured to supportgreat weight including premium stair materials including cast stone,marble and granite, as well as itself, at a relatively moderate cost.

Referring now to FIG. 2, there is shown staircase system 10 with each ofthe risers 16 and treads 18 removed therefrom to expose the framedstringers 20 adapted to support and receive the plurality of risers 16and treads 18. The stringers 20 are preferably comprised of highstrength metal material such as cold rolled steel so as to be adapted tosupport the staircase system 10 itself, as well as the extremely heavypremium materials supported thereon. Each stringer 20 of each section 12is seen to comprise of a plurality of framed portions generally shown at22 forming a rectangle and a space 24 therewithin. A curved planarfascia member 26 is secured to an inner and outer portion of the framedportions 20 to collectively form the inner and outer stringers 20, aswill be discussed in more detail shortly. Also shown in FIG. 2 is eachof the stair sections 12 secured to another stair section 12 eitherabove the upper step or below the lower step, as shown. Each stairsection 12 is seen to include a laterally extending frame member 30configured to be secured to the opposing frame member 30 of the adjacentstair section 12. The opposing frame portions 30 of adjacent sectionsare secured to one another, such as using fasteners or welding, asgenerally shown at 32.

Referring now to FIG. 3, there is shown an enlarged view of thestaircase system shown in FIG. 2 further detailing the securingmechanisms 32, shown as bolts and nuts, securing one step section 12 tothe next. Also shown is a plurality of laterally extending frame members40, commonly referred to as t-astragals, adapted to receive a bottomfascia (not shown) in a flush relationship.

Turning now to FIG. 4, there is shown an enlarged view of the lower stepsection 12 shown in FIG. 2 with the tread and riser portions removed toexpose the framed stringer portions 22. Each stringer 20 is comprised ofa plurality of riser flanges 42 and tread flanges 44, each shown to becomprised of a planar strip secured to one another, such as by welding.More specifically, a stringer flange 44 is seen to extend the width oftwo steps, with a first riser flange 42 extending upwardly from the midsection thereof, and also downwardly from the mid section thereof toform collinear aligned riser flanges in a “T” configuration. Thesemembers are preferably welded together and form the structurally rigidrectangular frame portion 22. The inner and outer fascia member 26 areeach preferably comprised of curved planar steel stock welded to theriser flanges 42 and tread flanges 44 to collectively form the framedcurved metal stringer 20.

Also shown is a plurality of openings linearly defined in the riserflanges 42 so as to facilitate securing a finished riser portion theretousing fasteners (not shown). The upper tread flange 44 forms the treadsupport configured to receive and secure a tread, comprised of a planarmember, such as wood, steel, plywood, but also can receive and supportextremely heavy materials including cast stone, marble and granite, aswell as elaborate railing systems including cast stone and wrought ironmaterials.

Advantageously, the framed stringer portions 20 can be configured withprecision tooling to very tight tolerances, even when curved as shown.As previously mentioned, curved staircases are the most difficultstaircases to create given the material characteristics themselves, suchas when under load, heated, or bent. When each step section 12 isultimately integrated to form the complete staircase 10, the precisionof each step section 12 creates a very precision staircase system 10.Advantageously, the need for a continuous extremely thick stock of steelas a stringer is eliminated, greatly reducing the cost of the stairsystem, while maintaining mechanical integrity. Further, if there is amisalignment at installation, only one section needs to be reworked orre-fabricated.

Referring now to FIG. 5, there is shown another view of the stairsection shown in FIG. 4 by itself.

Referring now to FIG. 6, there is shown the single stair section with aunitary riser and tread portion 50 extending between the respectivestringers 20 and secured to both the riser flanges and tread flanges,such as by welding. This unitary riser/flange member 50 may, if desired,receive the finished tread member and riser member, such as both mortarcompound and the tread itself. The unitary tread/riser member furtherprovides structural integrity in three dimensions for each step section12.

Referring now to FIG. 7, there is shown the completely assembled stepsection 12 with the unitary riser/flange sections 50. A pair of lowerflanges 46 are also shown secured to the underside of the framedstringers 20, as shown.

In one preferred embodiment of the present invention, for purposes ofillustration without limitation thereto, each step section 12 may beconfigured or comprised of ¼ inch CRS, whereby the tread flanges may be3 inch W× 3/16 inch CRS. The lower stringer flange may be 3 inch W× 3/16inch CRS, and the tread/riser plate may be 3/16 inch CRS. The t-astragalmay be 14 gauge with a 3 inch width, and a 1 inch vertical rise having athickness of ⅛ inch. Non-structural components for all tread surfacesmay be, for instance, 1⅝ mortar layer, 1¾ inch marble layer, and ¾ inchsheet rock and plaster for the facade. With these design specifications,the staircase of FIG. 1 meets the structural design loads for 1- and 2-family dwellings manual, prepared by the US Department of Housing andUrban Development Office of Policy Development and Research. Forinstance, the staircase system 10 adequately supports a concentratedlive load of 300 pounds (or 40 PSF, whichever is greater) assumed to actdirectly in the middle of each sub-tread to simulate a worst-casescenario. Each sub-tread, when analyzed individually, meets theserequirements.

Referring now to FIG. 8, there is shown another, more complex staircasesystem 60 configured according to the present invention. As shown,staircase system 60 includes a plurality of step sections 12, as well asa plurality of landing sections 62 interposed between a pair of stepsections 12 and secured thereto to create an elaborate floatingstaircase. In this design, the inner and outer welded composite sheetmetal stringers are comprised of 3/16 inch CRS, as is the tread/risers.Referring to FIG. 9, there an enlarged view of the lower landing 62designed to support floating conditions when configured with marble andmortar finishing materials. It can be appreciated, in view of FIG. 8,that this elaborate staircase system 60 has a significantly reducedstaircase dead weight, including the steel materials as well as themarble and mortar finishing materials, that is extremely moderateconsidering the size and complexity of the stair system 60, while stillmeeting the load requirements established by the US Department ofHousing and Urban Development Office of Policy Development and Research.Further, this staircase integrity is also verified by the SolidWorks®program created by SolidWorks Corporation of Concord, Mass., and isverified by a registered professional engineer.

To those skilled in the art of complex staircase systems designs, whichis truly a skilled art, they will appreciate the numerous advantages ofthe present invention. The modularity of the staircase system is justone technical advantage of the present invention, coupled with the factthat extremely precision high-load staircases can be realized at afraction of the cost of those comparable systems created with continuousstringers that are extremely expensive, difficult to manufacture, anddifficult to integrate, particularly in close locations. Moreover, theengineered staircase system can be manufactured prior to delivery andassembly at the stairs ultimate location to verify integrity,tolerances, and perform overall quality analysis. Further, there is atremendous time savings in both the manufacturing time for such astaircase system, as well as the installation time. Consider the factthat the staircase system shown in FIG. 1 can be easily installed byskilled labor into a home in one day without elaborate scaffolding orhuge labor cost. Further consider that a floating staircase of intricatedesign, high load, and that is aesthetically pleasing to discriminatehomeowners and guests, the numerous technical advantages of the presentinvention can be realized. Should one step section 12 ever need to berepaired or replaced, the stair case can be easily and quicklydisassembled, with the replacement section integrated therewith at avery nominal cost. It can be further appreciated that despite all thenumerous technical advantages in CAD design, complete tooling and designexperience, a delivered staircase system 10 may not always perfectly fitin its intended environment. In such cases, the upper section 12 may beredesigned to provide a high tolerance fit between the rest of thestaircase system 10 and the upper landing without having to replace theentire staircase or having to rework the entire staircase. Consideringthe cost of materials and labor, and the extremely competitiveenvironment for which staircase designers compete, the numerousadvantages of the present invention provide a highly desirable system,and allow staircases that are truly of art to be created.

Though the invention has been described with respect to specificpreferred embodiments, many variations and modifications will becomeapparent to those skilled in the art upon reading the presentapplication. It is therefore the intention that the appended claims beinterpreted as broadly as possible in view of the prior art to includeall such variations and modifications.

1. A stair system comprising: a plurality of steps each having a riserportion and a tread portion, each of the steps having a first end and asecond end; a first stringer secured to the first end of each said step,the first stringer extending generally transverse to each of the steps;and wherein the first stringer is comprised of frame elements definingstringer spaces therebetween, and further comprises a face flangesecured to the frame elements proximate the stringer spaces.
 2. Thestair system as specified in claim 1 wherein the frame elements compriseat least two stringer flanges extending generally parallel to eachother.
 3. The stair system as specified in claim 2 further comprising atleast one riser flange extending between the two stringer flanges,wherein one of the stringer flanges is positioned closely proximate oneof the step tread portions.
 4. The stair system as specified in claim 3wherein the riser flange extends transverse from a midsection of one ofthe stringer flanges to the other stringer flange.
 5. The stair systemas specified in claim 4 further comprising at least two said riserflanges extending between the two stringer flanges to form a generallyrectangular stringer frame portion.
 6. The stair system as specified inclaim 5 wherein the face flange is secured directly to the two stringerflanges and the two riser flanges.
 7. The stair system as specified inclaim 5 further comprising a lower flange extending beneath, and securedto, a lower portion of the stringer frame portion.
 8. The stair systemas specified in claim 2 wherein the face flange is generally planar. 9.The stair system as specified in claim 2 wherein the stringer flangesare generally planar.
 10. The stair system as specified in claim 2wherein the riser flanges are generally planar.
 11. The stair system asspecified in claim 2 wherein the face flange has a major outer surfacethat is curved.
 12. The stair system as specified in claim 2 wherein thestair system has a securing portion configured to securely join thestair system to another said stair system.
 13. The stair system asspecified in claim 2 wherein the steps of each said secured staircasesystems are in line with each other to form an ascending or descendingstair.
 14. The stair system as specified in claim 2 wherein the stairsystem has a securing portion configured to securely join the stairsystem to a landing member.
 15. The stair system as specified in claim 2wherein the securing portion comprises an opening configured to receivea fastener securingly extending to another said stair system.
 16. Thestair system as specified in claim 2 wherein the first stringer furtherincludes a railing mounting portion configured to receive and support arailing.
 17. The stair system as specified in claim 2 wherein therailing mounting portion includes a plurality of openings configured toreceive a railing system.
 18. The stair system as specified in claim 2wherein the first stringer is comprised of a metal material.
 19. Thestair system as specified in claim 2 wherein the riser portion and thetread portions are comprised of a planar metal material.
 20. The stairsystem as specified in claim 2 wherein the riser portion and treadportion are comprised of metal strips.
 21. The stair system as specifiedin claim 2 wherein the face flange comprises a singular planar piece ofmetal.
 22. The stair system as specified in claim 19 wherein the riserportion is a riser extending the width of the tread.
 23. The stairsystem as specified in claim 19 wherein the tread portion is a treadextending the width of the tread.
 24. The stair system as specified inclaim 19 wherein the riser portion and the tread portion each extend thewidth of the tread and are also a unitary member.
 25. The stair systemas specified in claim 22 wherein the riser is curved.
 26. The stairsystem as specified in claim 22 wherein the thread is curved.
 27. Thestair system as specified in claim 1 further comprising a t-astragalextending from the first stringer.
 28. The stair system as specified inclaim 18 wherein the first stringer is comprised of steel.
 29. The stairsystem as specified in claim 28 wherein the stringer frame elements arewelded together.
 30. The stair system as specified in claim 4 whereinthe at least one riser flange is generally perpendicular to one of thestringer flanges.
 31. The stair system as specified in claim 2 whereinat least one of the stringer flanges extends the width of two saidsteps.
 32. The stair system as specified in claim 2 wherein the stringerflanges extend parallel of one said step.